1. Technical Field
The present invention relates to a microscopic bubble generating apparatus which is used for aeration of a septic tank or blows microscopic bubbles into water of contaminated rivers, lakes, ponds and the like, thereby improving water quality.
2. Description of the Related Art
Aeration with the use of a blower is generally carried out for clarification of sewage water in a septic tank. For the purpose of aeration, air bubbles are blown out from a cylindrical plastic diffuser tube mounted at an exhaust side of the blower. However, the diffuser tube has a defect that the bubbles are swollen or contact with each other therein to burst, thereby disappearing.
In view of the aforementioned defect, Japanese Patent No. 3081983 discloses a microscopic bubble generating apparatus including two pumps having different discharge pressures. Discharge openings of the pumps are connected with each other by a piping. A supply pipe is connected to a suction port of the pump with higher discharge pressure in order to supply water together with air. A nozzle is provided on a suction port of the other pump with lower discharge pressure. Microscopic bubbles are generated from the nozzle by using the pressure difference during operation of both pumps. The disclosed microscopic bubble generating apparatus is provided with two water tanks, that is, a first water tank which stores water to be supplied to the pump with the higher discharge pressure and a second water tank storing water into which air bubbles are blown out. The apparatus is not constructed so that the water into which microscopic bubbles have been blown out is circulated between the pump and the second water tank. This results in a disadvantage that the extra water tank needs to be provided for storing water to be supplied to the higher discharge pressure pump.